obtain common salt from rock salt?

Question

Rock salt contains some insoluble impurities such as sand and clay. I want to know how to obtain pure common salt from rock salt.

Answer 1

Do not crush the rock salt as this will make the impurities harder to remove.

Dissolve the rock salt in very hot water and filter. If the filtrate (the water that comes through the filter) is colored, then you might need to treat it with charcoal to remove these soluble impurities.

Once you have a clear solution, allow some of the water to evaporate until the solution becomes saturated. A single seed crystal will start the formation of sodium chloride crystals from the solution. Stirring will keep the crystals smaller, otherwise you can end up with one very large crystal of salt.

This crystallization process is what does the final purification. The crystals formed will be almost pure sodium chloride.

Answer 2

1. crush rock
2. Dissolve crushed rock with water.
3. Filter sand and insoluble stuff
4. Evaporate water
5. collect salt.

Answer 3

I would imaging it is crushed, and then added to water to dissolve out the salt, and any sediment allowed to settle out. the salt water could then be allowed to run off, and the water evaporated off.

Answer 4

Either is fine in moderation but be sure you supplement you diet with iodide if you opt for sea salt